Unanswered Annoying crank bolts...

[MattyB]

One for the experienced mechanics here, calling @Gary...

I am converting my daughters 26” wheel MTB to 1x, but it currently has a worn one-piece Altus triple crank in the front which will need to go. I believe they are for a square taper BB, but before I bought the new crank I thought I’d double check; that is where the problem struck. Both crank bolts are without an Allen key hole, and my socket set doesn’t go big enough (max size is a 13mm). The bolt is quite deeply recessed and not marked with a size, but looks like it is probably 14-15mm.

Normally I’d pop to the bike shop but neither of my locals are open today, and I’m not sure they will be tomorrow due to the virus. I’ve asked a neighbour who may have a crank spanner, but it’s an outside chance. Does anyone know the typical size of crank bolts on what I assume is a square taper crank so I could buy the right sized socket online? Buying a whole new set seems overkill, but may be the only option even though this is probably the only time I will ever see a crank bolt like this! Thanks in advance.

 

[Ripping g]

That will be a old style crank if i remeber they were a 15mm socket if you dont need the nut or crank arm try using hammer n screwdrive

 

[MattyB]

That will be a old style crank if i remeber they were a 15mm socket if you dont need the nut or crank arm try using hammer n screwdrive

Thanks - you were quite correct, I managed to get it off with a 15mm socket from the neighbour. Why they still fit such bolts though is beyond me - does it really save any money? The bike (a 26" wheel Scott Roxter Disc) may not be in the very top echelon of kids bikes but at £449 new I'd have thought they could have stretched to proper crank bolts! And another thing... Why do all these kids bikes still have straight taper head tubes when there are almost no straight taper forks these days? I've managed to finder a Suntour Raidon Air that should fit, but it was literally the only option that had QR and straight taper. Grrrr...

It will be the envy of her mates by the time I'm finished with it though - 1x10 Deore, air fork and (once she's tall enough!) a dropper.

 

[Gary]

It should be a 14mm hex. (not 15mm).
15mm sometimes fits loosely though.

To remove the crank arms you now need a threaded square taper crank puller.
And you will also need to choose your replacement chainset paying attention to recommended axle length (or fit a new suitable length sq taper BB (more tools required)

 

[Gary]

Rockshox still do the dart in 26" straight 1 1/8 QR
It's fine for a kids bike
And cheap